Typically, liquid hydrocarbons (commonly referred to a crude oil) are extracted from natural underground hydrocarbon bearing geological formations through the drilling of a relatively small, and more or less constant, diameter wellbore (most often from approximately four inches to eight inches in diameter) from the surface of the ground downwardly through the geological formation that harbours the hydrocarbons. Most commonly, a down-hole pump is then inserted into the wellbore in order to pump the effluent produced from the geological zone of interest, including liquid hydrocarbons or crude oil, to the surface. Typically, such pumps are driven through use of sucker rods that extend from the downhole pump upwardly to the surface and are operated in a reciprocating manner by an electric or gas motor connected to the sucker rod by a series of gears and linkages. The above ground structure that is responsible for reciprocating the sucker rod is often referred to as a pump jack. In addition to the downhole pump, sucker rod and pump jack, traditional oil wells also contain a steel casing which is cemented in place and a production tubing running from the downhole pump to the surface through which the oil is pumped. The production tubing is usually secured to the bottom portion of the cased wellbore by a centralizing anchoring device and is usually subjected to wear and tear caused by the reciprocating sucker rod and through the transportation of effluent that typically has corrosive and scaling characteristics which foul and/or impair the pumping efficiency.
It will be appreciated that due to the nature of the pumping and production equipment required for a typical oil well, the equipment necessary to operate a single well represents a significant capital investment and significant ongoing operating expenses to maintain and operate such equipment continually. For wells that produce high volumes of crude oil, the capital and operating costs of the required equipment is usually more than offset by the revenue generated from the crude oil that is produced. However, low producing or low volume oil wells may, in many cases, not produce sufficient volumes of oil to offer sufficient cash flows during low crude oil price levels to justify the exploitation of the geological zone of interest and/or the on-going operation of such marginal oil wells.
There is therefore the need for a method of extracting liquid hydrocarbons from underground hydrocarbon bearing formations having reduced or low hydrocarbon flow rates which requires a less significant capital outlay and that has lower operating costs. Similarly, there is a need for a method that may be used to extract hydrocarbons from underground geological formations where traditional oil extraction methods have been utilized but, due to reduced hydrocarbon flow rates, are no longer financially practical to develop and exploit.